This is a competing continuation application for a NIDA Postdoctoral Research Training Program at the Alcohol and Drug Abuse Research Center, McLean Hospital and Harvard Medical School. The program goals are to train M.Ds and Ph.Ds in clinical and preclinical research on drug abuse, and to prepare trainees for an independent research career. Trainees can participate in interdisciplinary studies involving Behavioral Science, Brain Imaging, Endocrinology, Medicinal Chemistry, Neurobiology, Neuroscience and Pharmacology with mentors from a 13-member faculty. These disciplines are integrated across basic and clinical projects to study the influence of gender and neuroendocrine hormones on the abuse-related effects of drugs, and to evaluate novel biologic and pharmacologic drug abuse treatment medications. The program is individually tailored to meet each trainee's interests and career goals. Clinical fellows can be trained in translational research on drug abuse treatment, clinical laboratory evaluations of new treatment medications, neuroendocrine and brain imaging measures (fMRI) of the acute and chronic effects of abused drugs. Preclinical fellows can be trained in medicinal chemistry, brain imaging techniques and operant behavioral procedures designed to evaluate candidate treatment medications. Trainees can also study the interactions between abused drugs and the hypothalamic-pituitary-adrenal and the hypothalamic-pituitary-gonadal axis, and analyze the analgesic efficacy of novel opioids. Trainees initially participate in one or more ongoing research projects with their mentors. Then trainees design an independent research project, compatible with the overall research goals of the program, that could form the basis for a research application. Trainees are taught about ethical issues that affect research, and learn about IRB and IACUC procedures. Trainees take courses, participate in a journal club, attend lectures and present research findings at scientific meetings. Six postdoctoral fellows (levels 0, 2,4,7) will be trained for 2 or 3 years. Twenty-seven of our 30 recent trainees now have independent research careers. Drug abuse is a major public health problem that afflicts many individuals and their families. Training young scientists in interdisciplinary translational research is the best strategy for learning about the multiple determinants of this complex biobehavioral disorder, and for developing more effective approaches to treatment and prevention.